"Berichte des Instituts fur Chemie der Treib-und Explosionsstoffe der Fraunhofer Gesellschaft, Jahrestagung 1975" [Reports of the Institute of Chemistry of Propellent Substances and Explosives of the Fraunhofer Society, 1975 Annual Congress], Karlsruhe, 1975, pages 185-194, reveals that IR radiation of certain wavelengths is selectively absorbed by atmospheric components as a result of which so-called "atmospheric windows" develop. These windows are found at wavelengths of 0.7-1.5.mu. and all the way to 8-12.mu.. This knowledge and application of Rayleigh's law led to the use of various forms of powder as smoke for camouflage purposes (cf. German Patent Application Published for Opposition DE-AS No. 27 29 055).
These powders, however, produce only unsatisfactory optical concealment and have a relatively high settling rate.